Saint Tarasius (mid-8th century-February 25, 806) was Patriarch of Constantinople from 784 until his death in 806. He was also chief secretary of Empress Irene II, who instigated Tarasius' election to the patriarchy, even though he was a layman at the time.
As a part of his policy of improving relations with the church in Rome, he pesuaded Empress Irene to convoke, together with Pope Adrian I, what came to be known as the Second Council of Nicaea in 787, over which he presided.
Later in his patriarchy, he suffered from criticism of his alleged tolerance of simony, and of his handling of the divorce of Irene's son Constantine VI. Under severe pressure from Theodore of Studios, he excommunicated the priest who had conducted Constantine's second marriage.
When Nicephorus I dethroned Irene as Byzantine emperor, Tarasius crowned Nicephorus as the next emperor.